Tool carrier of a CNC milling machine

U ovome radu ukratko je opisana povijest i razvoj CNC obradnih centara, objašnjeno je numeričko upravljanje te su detaljno opisani načini izmjene alata. Razmotreno je par različitih koncepata te je izabrano optimalno rješenje. Zatim je napravljen proračun radi provjere sigurnosti jer su svi dijelovi namjerno predimenzionirani kako bi se osiguralo upijanje vibracija, a time omogućila visoka preciznost obrade. Prvo je proračunat sklop za glavno gibanje, odnosno pogon alata. Proračunate su sile i snage rezanja, provjerena su vratila na sigurnost te je dimenzioniran zupčasti remen i remenice. Zatim se proračunavao sklop za izmjenu alata. Preko dinamičkih momenata tromosti dobila se potrebna snaga za izmjenu alata, a zatim se dimenzionirao pužni prijenosnik. Nadalje, proračunati su svi nosivi vijčani spojevi te je ukratko objašnjeno rješenje izvedbe pomaka u x,y i z smjeru. Paralelno uz proračun rađen je i model konstrukcije u programskom paketu CATIA. Nakon modeliranja izrađena je i tehnička dokumentacija glavnih sklopova koja je dana u prilogu. Na kraju ovog rada je spomenuto i nekoliko konstrukcijskih rješenja kojima su se riješili problemi pozicioniranja.This thesis briefly describes the history and development of CNC machines, it explains numerical control and gives an in-depth description of tool changers. A couple of concepts are taken into consideration and an optimal version is chosen. Afterwards, a calculation is made in the purpose of verifying the safety factor because all of the machine parts are intentionally over-dimensioned so that they could absorb vibrations and with that, enable high-accuracy machining. First calculations were made on the main motion assembly, which actually drives the tool. The forces and powers of cutting were calculated, shafts were checked for their safety factor and then the toothed belt was dimensioned. After that, the assembly for tool changing was calculated. By determining the dynamic moment of inertia, it was possible to calculate the necessary power for tool changing, and after that a worm gear reducer was dimensioned. Afterwards, all the screw joints that carry loads were calculated and a solution for the motion in x,y and z axes was briefly explained. Simultaneously to the calculation, a model was being designed in the program package CATIA. After designing the model, technical documentation of the main assemblies was made, which is attached to this paper. At the end of this paper a few design solutions, which solved the problem of positioning, were mentioned and explained